From the earliest hand driven looms to the automatic knitting machines of the present, automation widely adopted in today's modern textile industry. With raised living standards, the general public has an increased appetite for high quality garments. To meet the consumer's growing requirements, the knitting industry has to speed up production.
At present, knitting machine manufacturers generally sell the finished knitting machines and transfer the machines to textile producers after installation is completed. The knitting machines are used to produce various types of fabrics. During knitting operation, if a malfunction occurs in the knitting machine that the user cannot fix or readjust, they inform the vendor immediately. The vendor dispatches technicians for onsite repairs and maintenance to restore the knitting machine to normal operation condition.
The conventional knitting machine controller uses a Programming Logic Controller (PLC) to drive the machine. However, transmission stability is often affected by the external environment or other factors. The design and application of the controller for a conventional knitting machine may be depicted as follows:
Referring to FIG. 1, in an architecture based on a PLC 13, linking to a communication module 12 is mainly accomplished through an RS232 line 17. The communication module 12 has one end connected to a touch panel 11 through the RS232 line 17, and another end to a connection dock 14 also through the RS232 line 17. The connection dock 14 is connected to a host end 15 through an RS485 line 18. Whilst communication speed and stability are less likely to be affected by the external environment, in terms of the RS232 line 17, it has to take into account the speed and program capacity of the PLC 13. The program size of the PLC 13 is directly proportional to the program scan time. Namely, a larger program requires a longer scan time. Taking existing programs, the time required to scan a program is 24 ms. This is of great concern to the whole system. In this time interval any thing could happen. In the event of an incident taking place, and the scan time having just ended or not yet begun, it cannot be responded to by the system. The delay could create unpredictable damage to the system. Due to environmental interference, inherent quality, and quality problems of the inner elements of the PLC 13, the conventional PLC 13 generally can control only one circular knitting machine 16. To control a plurality of circular knitting machines 16 by a plurality of PLC 13 modules, the cost is significantly higher. This is an issue remaining to be overcome.